1. Field of the Invention
The present invention relates to a metallic container cover and, more particularly, to a scoring die to be used for manufacturing an easy open can end which can be manually opened with ease partially or wholly of a can cover using a laminated steel sheet, a method for manufacturing the easy open can end, and the easy open can end.
2. Description of the Related Art
The easy open can end uses aluminum mainly for its material. A lacquered steel sheet is inexpensive as the material but needs a repair-coating step after worked, so that it has less economical merits. For these situations, it is under the situation that the steel sheet is not positively utilized.
Under this background, various trials have been made by devising the cover working method and by using the laminated steel sheet according to the working method for, omitting the step of repair-coating the easy open end made of the steel sheet.
Patent Publication 1: JP-A-06-115546 has tried a non-repair by devising the method for working a V-shaped score of the prior art, in which a flat portion is formed on the score bottom by using a polyester resin. Patent Publication 2: JP-A-09-234534 has devised the scoring method while regulating the thickness and the breaking elongating of the resin layer. Patent Publication 3: JP-A-11-01775 has tried the non-repair by using a curved die in the scoring work.
Here will be described information on the technical publications of the prior art.
Irrespective of these inventions, however, the cover made of aluminum has a monopoly position in the market. In not only the beverage can market but also the food can market, along with the easy opening trend, it is under the situation that the easy open end of aluminum is rather increasing. This situation verifies that the merit to make a change from the cover of aluminum to the cover of a laminated steel sheet is not accepted by the market.
The reason why the laminated steel sheet covers are hard accepted in the market is thought to come from the fact that some of them can be applied but most of them cannot in dependence upon the requirement levels such as the contents to be charged into the can, the design of the can, the cover manufacturing method or the manufacturing method. This insufficient application is thought for the following reason. If the scored remaining portion is thinned, the openability is improved, but a strict working is required for the film. This makes the non-repair difficult so that the openability and the non-repair are not compatible.
By solving the problems thus far described, the laminated steel sheet is really enabled to participate into the market. This real participation of the inexpensive laminated steel sheet into the market is not limited to a reduction in the can cost. It is needless to say that the whole steel can is excellent in the viewpoint of recycling, but the steel itself has a lower load on the environment than aluminum. Therefore, this transfer of the material has a high industrial meaning.